1. Field of the Invention
The subject of the invention is a laminator to laminate a film onto a support.
2. Description of Related Art
One laminator has an upper pressure nip formed between a fixed roller and above it, a pressure roller. Into the nip can be fed the support from a feed plate and a film, with a protective cover sheeting removed, from an upper supply roller. By means of a shifting device, the upper pressure roller is switched back and forth from an idle position, in which the upper pressure nip is open, to an operating position, in which the upper pressure nip is closed, and the roller drive is started.
A known example of such a laminator is the "CROMALIN.RTM. Laminator 2700". It is used in conjunction with a color proofing system. Exposure of the laminate, which consists of a sheet-shaped support and a light-sensitive film, results in tacky areas, to which, after the cover sheeting is removed, toner adheres. After lamination, the composite is slit on a cutting platform on the outlet side. The rest of the film web remains with its leading edge in the open pressure nip ready for the next lamination.
For four-color printing, a support must be provided successively with four light-sensitive films, which, after exposure, are treated with different toners. It is frequently desirable to apply a protective film to cover the topmost toner layer. For this purpose, a protective film must replace the light-sensitive film in the laminator. This exchange must subsequently be reversed, resulting in considerable time loss and high film waste. The alternative of installing two adjoining laminators requires doubling investment costs and is often not feasible because of space limitations.
U.S. Pat. No. 3,547,730 discloses supports, such as plates, laminated on both sides with a light-sensitive web by passing the layered composite through a pressure nip between two heated rollers. It is thereby possible theoretically to laminate one side by omitting one light-sensitive web. However, each change of material requires re-threading the light-sensitive web into the pressure nip.